Formwork girders



Nov. 14, 1961 o. Hnilzs 3,008,556

, a FORMWORK GIRDERS Filed Feb. 15, 1957 4 Sheets-Sheet 1 Inventor:

1961 o. HINZE 3,008,556

FORMWORK GIRDERS Filed Feb. 15, 1957 4 Sheets-Sheet z Nov. 14, 1961 o. HlNZE 3,008,556

FORMWORK GIRDERS Filed Feb. 15, 1957 4 Sheets-She t z Inventor:

Nov. 14, 1961 o. HINZE 3,008,556

FORMWORK GIRDERS Filed Feb. 15, 1957 4 Sheets-Sheet 4 jm enton' United States Patent 3,008,556 FORMWORK GIRDERS 1. OttoHinze, Hegelstrasse:4, Hannover=Kleefeld, Germany .EilediFeb. .15, .1957, Ser. No. 640,364 6 ger s. gl. .1 s9. 37

Theprese-nt,inventionrelates to telescopically extensible and contracta ble girdershaving at least .one inner girder part, ,wherebythe length ofsaid inner girder part of both girder parts. The twogirder partshave about an equal moment of resistance against bending; also the strength of their proiiles for receiving horizontal forces is approximately the same.

Such girders are used predominantly as formwork carriers (carriers for timibering in construction works) and thus subject to great strain because frequently theyare thrown from great height; moreover, they are pulled and dragged along on the floor without consideration of any protruding parts; they are under the effectof rough construction Work and temperature influences; and they are also subject tothe chemical influenceof the building materia'ls and, very much in contrast to the conditions of other machinery and implements operating in closed factories where there is constantly the required supervision of the constructional status, these girders are notsupervised in any way. For the same .reason, formwork girders of this kind cannot have any loose parts which are always lost. Formwork girders of this kind are also sent from one construction site to the next without inspection, but, on theyother hand, these girders andparticul arly formwork girders are to carry heavy loads. If they do not meet this particular requirement, a building can fall in at great danger for people and material.

height after use onthe top floor of a building and even when striking other girders and other objects which had been thrown previously, they are not damaged nor deformed and do not otherwise lose their operational efliclency.

It is a further object of this invention ,to so provide the aforementionedlocating means that there are no loose parts which could belost.

It is finally an object of this invention to reinstate the curvature of girders which was lost due to the strains mentioned. This curvature is given to the individuallparts of the girder already when the profiles are rolled so as to achieve that the girder, under the load it carries, is deformed only to .such an extent that it is limited by planes on both sides. If such {a girder had nocurvature nor overarc, ,it would bend downwardly Under its load, and its lower border line segen from helowwould be convex. ,If such girders wereused as formwork girders for ceilings, yi't would result-in ceilings which areiormed convexly .at the lower side. Inorderto later overcome the convex course of a ceiling, ,a considerable quantity of plaster and great amount of work are needed so that, consequently, ,bent telescopiccarriers are used. But due to the above-mentioned strain the original bent or .curvature is decreased and may even disappearentirely or, the girder may also receive =a.cur vatur e in opposed direction, to :the other side. For .this reason, means are provided which ,are to reestablish the partly or completely lost curvature,

ice

.Thedr-awing represents a number of .illustrativeembodiments'.

:FIG, lis an enlarged view showingthe right-hand end of a formwork girder which consists of. an. ont,er grrder part. and an inner girder part.

.FIG. 2 is in its left-hand, pant a vertical cross-sectional .view taken throughthe formwork. girder on.]ine,.II II ,inits rightehand parta vertical cross-sectional v iewtaken on line II II of FIG; 1.

FIG. 3 showsthe formwork girder according to FIG. 1

,on a smaller scale, ,in a position in which the inner girder part is entirely pulled out of the outer girder parttothe right so that the torntwork girder consisting of .the :two parts, has its maximum length.

"FIG. 4 corresponds ,to FIG. 3 with the difference that the inner girder partjs entirely .pushed into vthe outer girder partisothat the-lformwork girder h-as its length.

FIG. f5 shows the outer 'andiinner girder parts with the inner girder pant extended towards the right.

"In FIG. 6 the inner girder part has been pushedjinto the outer girder part so that "FIGS. 5 and 6 shows the same formwork girder with the Inaximumand lengths,,respectively.

'FIG.'.7 is a somewhat enlarged view of the outer girder art. p Fig. 8 is a view on a similar scale showingthelinner girder part.

FIG. '9 is a vertical cross-sectional .view of the outer girder part. FIG. '10 is .a veitical cross-sectional view of the inner girder part.

'FIG. 11 shows the assembly of :the fastening means with the-proposed bridge member, whereas FIG. "12 is a top plan view ofthe wedgeqmember.

"FIG. 13 is a vertical cross-sectional of the bridge member and wedge assembly.

FIG. 14 is an enlarged view showing the right-hand end of a 'formwor'k girder consisting of outer and inner girder parts.

FIG. 15 isin its left-handpai-t 'avertical cross-sectional view of-the jformwor'k girder ,cn line,XV XV and in its right-hand part a vertical cross-sectional view taken on 1ine-XV XV of FIG. 14.

"FIG, 16-is aviewyon asrnaller scale showing the formwork girder of FIG. 14 in a position in which the inner girder-part has been pulled to the right entirely out of the outer girder part so that the ;formwork girder consisting of both pa'rtsihas its length.

FIG. 17 is similar to FIG. 16 with the difference that the inner girder part has been pushedentirely into the outer 'girder'part so that the formwork girder has its minimum length.

"In all figures, numeral fldes'ignates the upper chord of the outer part of the formwor-k girder; that. upper chord consists of a drawn section. The lower chord of the outer girder part consists of a round bar 2. Diagonal bars are provided 'to connect the upper chord '1 and lower chord 2;-in this embodiment these bars are continuous, a zig-zag connection of round bars ortubes '3 being welded to each of the two flanges of the upper chord 1. The zig-zag diagonal connections 13 are also welded'tothe lower chord'z on both sides thereof so that the outer girder parthas a V-shaped profile when consideredinits basic linear shape. The outer girder part 1, "2 3 is slanted at its right-hand end. The slant is formed by the rod-shaped straps, 4;, which connect the right-hand ,end of the upper chord 1 ,to the right-hand end of the lower chord Zin a manner which will be described more fullyjhereinafter. ;In order to enable that connection to be established, a U-shaped pocket 5 is welded to theright hand endofthelowerchord-Z in such 'a manner that the right-hand end of the lower chord 2 is disposed in that part of the cavity 6 of the pocket which directly adjoins the bottom of the pocket 5. In the rest of the cavity 6 the lower chord 7 of the inner girder part (that lower chord is rectangular in cross-section) is guided and the remaining space between the parts 2 and 7 is partly occupied by the wedge member 8, which is a means for locating the inner and outer girder parts in any relative position, and partly by the guide member 18, as is shown particularly in FIG. 2. Since the upper chord of the inner girder part is formed by the two angles 9, 10 which adjoin the upper chord 1 from the inside, the inner girder part is wedged against the outer girder part, as has been mentioned hereinbefore. A diagonal connection 11 is again provided to connect the upper chord 9, 10 and the lower chord 7 of the inner girder 7, 9, 10, 11.

The diagonal connection 11 is again formed as a zigzag round bar or tube. Different from the outer girder part, however, where two diagonal connections are provided to form the V-shaped basic profile of the crosssection, only a single Zig-zag bar or tube 11 is sufficient. In order to ensure a perfectly safe connection of the pocket 5 to the outer girder part 1, 2, 3, additional straps 12 are provided in addition to the straps 4 and consist of vertical rods which connect the sides of the upper chord 1 to the outside faces of the pocket 5; the connection may again consist of welds. To prevent the inner girder part 7, 9, 10, 11 from being pulled entirely out of the outer girder part 1, 2, 3, a retaining means is provided at the left-hand end of the inner girder part 7, 9, 10, 11. In the example shown that retaining means consists of a threaded bolt 13 having a head nut and a lock nut. The engagement of that retaining means 13 on the left-hand end face of the pocket 5 will prevent the inner girder part from being pulled entirely out of the outer girder part. The wedge member 8 is also prevented from being pulled out entirely. Contrary to the retaining means 13, however, which must be detachable, the retaining means 14 for the wedge member 8 may be permament so that it is sufficient to provide the wedge member at that point with projections formed by the material of the wedge member itself in order to prevent the wedge member 8 from being pulled entirely out of the pocket 5. In that case the wedge member must be inserted from the tip into the cavity 6 before the inner girder part 7, 9, 10, 11 is introduced into the outer girder part 1, 2, 3. Once the inner girder part has been introduced, its lower chord 7 will act as a positive retaining means for the wedge member 8 so that in spite of the fact that the latter is a loose part in itself it can never be lost when the form/work girder has been finally assembled.

Contrary to girders having butt-jointed upper chords and connecting means of variable length for the lower chords, telescopic girders cannot be subsequently increased or reduced in height. In order to enable the production of perfectly flat carrying structures with said girders in spite of the inevitable elastic deformation of said girders under the weight of the building material they are inherently given an appropriate camber. It has been found that in spite of a permanent camber of that type the material of such formwork girders will fatigue most rapidly as a result of the continually repeated deformations and other stresses encountered in use, for instance, when they are thrown so that the girders tend to flatten. Thus the originally provided camber disappears and such formwork girders can no longer be used for making fiat carrying structures, such as floors and ceilings. In order to prevent this the lower chords 2 of the outer part of the formwork girder 1, 2, 3 comprise three turnbuckles 15, which comprise, e. g., a tubular nut having threads of opposite hand engaged by the ends of lower chord parts 2 formed with mating threads. Such tubular nuts, however, have no bores for the insertion of pins or other readily operable means for turning the same because an incorrect turning of the turnbuckles 15 might impart to the outer part of the formwork girder a camber which was not originally provided or which is not to be adjusted. For this reason a turning of the turnbuckles 15 is possible only with special pincers (pipe pincers) designed or provided for this purpose. Thus only a skilled Worker who possesses those special pincers and has been trained for this operation can adjust the rise of the camber. The left-hand end of the outer girder part and the right-hand end of the inner girder part have at 16 and 17 means for placing the formwork girder on existing walls or on supporting frameworks, columns or other supports. These supporting tongues 16, 17' are desirably forked.

In the second illustrative embodiment shown in FIGS. 5 to 13 a bridge member is provided to enable a nonrigid and, therefore, lighter construction of the lower chord of the inner girder part.

As is apparent from FIGS. 5 and 9 the outer girder part comprises again an upper chord 1, which consists of a profile member, a bar-shaped lower chord 2 and a diagonal connection between the chords; that diagonal connection consists of two zig-zag round bars 3. Instead of round bars 2 and 3 these members could also consist individually or entirely of tubes.

The inner girder part, whose construction is apparent from FIGS. 8 and 10, consists of a profile bar, namely, a cup profile 19, forming an upper chord and a bar-shaped lower chord 7. Contrary to the construction of the outer girder part, which is basically triangular in cross-section, the diagonal connection is disposed only in the central or web plane of the inner girder part and is formed by a simple zig-zag round bar 11. The upper chord 19 may be formed with simple recesses for receiving the upper bends of the round bar 11; the edge boundaries of said recesses are subsequently welded to the diagonal bar 11. In the present embodiment, tongues 20 have been struck and bent out of the upper chord 19 to form lateral stops for the diagonal bar 11. The connection is additionally protected by welds, not shown.

When the outer and inner girder parts thus described are in that condition in which the inner girder part has been inserted into the outer girder part they form a formwork girder.

In order to provide for a certain position of the inner girder part relative to the outer girder part during the use of the formwork girder with the resulting length, the following additional measures are provided according to the invention, reference being had to FIGS. 11 and 13.

As is apparent from said two figures a wedge member 8 is again provided for locating the inner girder part in the outer girder part; that wedge member 8 is T-shaped in cross-section. It forms at 21 a wedge nose whereas the part of the wedge member which corresponds to the horizontal upper flange of the T has hook-shaped enlargements 22. The wedge member 8 engages the bridge member 23, which is U-shaped in cross-section, as is ap parent from FIG. 13. The lower chord 7 of the inner girder part and part of the diagonal connection 11 are accommodated in the resulting cavity 24. Lugs or tongues 26 are struck out of the bridge member 23 to leave openings 25 and are bent downwardly to provide a guide for the wedge member 8. Additional recesses 27 are formed by bending out lugs 28, which act as stops, over which the bridge member 23 is guided on vertical rods 29, in which the diagonal connections 3 of the outer girder part terminate, as is apparent from FIGS. 12 and 13. Since the upper chord 19 of the inner girder part 19, 7, 11 engages the upper chord 1 of the outer girder part from the inside, the inner girder part 19, 7, 11 will be forced against the outer girder part 1, 2, 3 when the wedge member 8 is in an appropriate position; thus the two girder parts are located in the desired relative position. If the wedge member 8 directly engaged the lower chord 7 of the inner girder part, as was the case in the preyiouslydescribedembodiment, the wedge member-8, un-

.less it. was arranged in a special manner according tothe invention would impart a bending stress to that lower chord between the barsllfland 11" of the diagonal connection 11 of ,the inner girder part'19, ,7, 11 so that the im ortan par cul y wor r s the bridge member 23 by distributing theoccurrenceof the wedge forces over a range whose lengthexceeds :the extent of thewedge member 8- wi ll cause saidforces to reach;at leastzthe nodesSI], 3;1 .so th at a direct dissipation of said wedge forces to the diagonal connection 11 and thus to the upper ,chords 19, .1 .is ensured, which .wilLeasily take up and dissipate said forces in conjunction with the other members of each girder.

The wedge member 8 is carriedby a thrustmember 32, which rests on the lower chord 2 of the outer girder part. The end 33 ofthe upper-chord 1 of the outer girder 1, 2, 3 is again connected by the diagonal connec- 'tion 4 to the lower chord "2; thus the outer girder part is slanted like a triangle at its right-hand end. On the opposite side the outer girderpart 1, 2, 3 has the supportingclaws :16, which-are desirably forked. Such claws are also provided at 17 on the inner girder part 19, 7, 11 (see FIGS. 6 and 7).

In this case it is also desirable to impart a slight camber to such formwork girders in order to ensure that camber to be reduced under the weight of the building material, whereby perfectly flat floors and ceilings can be obtained. According to experience the formwork girders fatigue relatively rapidly whereby the small rise of said camber disappears. In addition to the fatigue it is also significant that these girders are thrown in most cases when they are being loaded and unloaded and the resulting deformations eliminate the camber. In order to prevent this a turnbuckle 15 is again inserted in the lower chord 2 of the outer girder part 1, 2, 3 and is engaged by the adjacent lower chord ends having screw threads of mutually opposite hand. Thus the formwo-rk girder can again be given the necessary rise when required.

In FIGS. 14 to l7, 1 designates again the upper chord of the outer part of the formvvork girder; that upper chord consists of a drawn profile. The lower chord of the outer part of the girder consists of a round bar 2. Diagonal bars are provided to connect the upper chord 1 and the lower chord 2; in this embodiment these bars are continuous, a zig-zag connection 3 of round bars or tubes being welded to each of the two flanges of the upper chord .1. The zig-zag diagonal connections 3 are also welded to the lower chord 2 on both sides thereof so that the outer girder part has a V-shaped profile when considered in its linear basic cross-sectional shape. The outer girder part 1, 2, 3 is slanted at its right-hand end. The slant is formed by the rod-shaped straps 4, which connect the right-hand end 33 of the upper chord 1 to the right-hand end of the lower chord 2 in a manner which will be described more fully hereinafter. In order to enable that connection to be established, a U-shaped pocket 5 is welded to the right-hand end of the lower chord 2 in such a manner that the right-hand end of the lower chord 2 is disposed in that part of the cavity 6 of the pocket which directly adjoins the bottom of the pocket 5. The wedge member 34 is a means for locating the inner and outer girder parts in any relative position and is guided in another part of the cavity 6. The wedge member 34 is also U-shaped and embraces the lower chord 7 of the inner girder part 7, 9, 10', 11 from below so that the lower chord 7 can slide through the wedge member 34 when the latter is not forced against the pocket 5. The wedge member 34 rests on a filling member 18 in the pocket '5. Since the upper chord of the inner girder part is formed by the two angles 9, 10, which engage the upper chord 1 from the inside, the forcing of the wedge member 34 against the parts 7 and 18, 2, *5 will cause the inner .girder part tobe wedged against the outer girder part. A diagonal connection .11 is provided, of course, between the upper chord-9, 10 and the lower chord 7 of the inner girder part7, .9, 10, 11. The diagonal connection 11 is again formed as a 'zig-zag round bar or tube. Different fromthe outer girder part, where two diagonal connections are provided to form the V- .shaped basic profile of the cross-section, only a single zig-zag bar ortube 11 is sufficient. In order to ensure a perfectly safe connection of the pocket '5 .to the outer girderpart 1, 2, 3 additional connections'29 are provided in addition to the straps 4 andconsists of vertical rods bent from the diagonalmembers3 and connecting the pulled entirely out of the outer girder part 1, 2, 3 a

retaining means is provided at the left-hand en d offithe inner girder part 7, 9, '10, 11. In the present example that retaining means consists of -a;threaded b olt '13having ahead nut and alock nut. The engagement of thatretaining means 13 on th e left-hand end face of the pocket 5 will preventthe inner girder part from being pulled entirely out of the outergirder part. The-wedgemember 34 is also protected from being pulled out entirely. Contrary to the retaining means 13, which must be detachable, the retaining means 35 for the wedge member may be permanent. It is sufiicient, e.g., to provide the wedge member at that point with projections formed out of the material of the wedge member in order to prevent the wedge member 34 from being pulled entirely out of the pocket 5. In that case the wedge member must be introduced from the top into the cavity 6 before the inner girder part 7, 9, 10, 1 1 is introduced into the outer girder part 1, 2, 3. Once the inner girder part has been introduced, its lower chord 7 will act as a positive retaining means for the wedge member 34 so that in spite of the fact that the latter is a loose part in itself it can never be lost when the formwork girder has been finally assembled. In the present example the wedge member 34 is not provided with hook-shaped projections for engaging the diagonals 3 but retaining means 35 are provided in the form of elongated eyes which constitute stops that engage the part 5. The length of said retaining means 35 is such that the necessary tightening and loosening movements of the Wedge member 34 are not hindered.

The left-hand end of the outer girder part and the righthand end of the inner girder part have at 16 and 17 again means for placing the formwork girder on existing walls or supporting frameworks, columns or other supports. These claws 16, -17 are suitably forked.

What is claimed is:

1. A girder, particularly a formwork girder, which can be telescopically increased and reduced in length, said girder comprising, in combination, at least one outer girder part, at least one inner girder part, said girder parts comprising at least chords and diagonals connecting the chords, means for locating one inner girder part relative to said outer girder part, a bridge member engaging one of said chords and the locating means, the contact area between said bridge member and said chord exceeding the contact area between said bridge member and the locating means, said locating means consisting of a wedge member, said bridge member consisting of a member of U-shaped section and the chord to be located extending through said bridge member.

2. A girder as set forth in claim 1, said bridge member being disposed between the lower chord of an inner girder part and the lower chord of an outer girder part, the length of said bridge member exceeding the distance between two successive nodes between diagonals of an inner girder part and the chord of said inner girder part.

3. A girder as set forth in claim 1, stops effective between the bridge member and the outer girder part and permitting movement of the bridge member in the direction toward and away from the chord of an inner girder part but preventing the movements of the bridge member in the direction of the chord.

4. A girder as set forth in claim 1, stops effective between the bridge member and the outer girder part and permitting movement of the bridge member in the direction toward and away from the chord of an inner girder part but preventing the movements of the bridge member in the direction of the chord, said bridge member being constructed to engage the wedge member, stops eifective between the bridge member and wedge member and adapted to guide the wedge member by means of the bridge member.

5. A girder as set forth in claim 1, said girder comprising further a thrust member between wedge member and said outer girder part, said thrust member being adapted to transmit the Wedge forces on the chord of said outer girder part.

6. A girder, particularly a formwork girder, which can be telescopically increased and reduced in length, said girder comprising, in combination, at least one outer girder part, at least one inner girder part the length of Which is substantially equal to the length of the outer girder part with both girder parts having profiles of approximately equal moment of resistance against bending and equal strength against arising horizontal forces, 'means for locating one inner girder part relative to said References Cited in the file of this patent UNITED STATES PATENTS 1,888,181 Riesbol Nov. 15, 1932 FOREIGN PATENTS 11,297 Switzerland Mar. 17, 1895 1,064,850 France Dec. 30, 1953 157,744 Australia July 21, 1954 181,953 Austria May 10, 1955 

